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Process for preparing 4-aminodiphenylamine

a technology of aminodiphenylamine and aminodiphenylamine, which is applied in the preparation of organic compounds, amino compounds, organic chemistry, etc., can solve the problems of reducing the yield of valuable 4-adpa, reducing the volume productivity of this reaction, and reducing the total reaction time.

Active Publication Date: 2017-07-18
NOCIL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0008]The volume productivity of this reaction can be substantially improved by carrying out the process either in batch or continuous manner, wherein, nitrobenzene is added all at once thereby providing a substantial reduction in the total reaction time by avoidance of the three hour nitrobenzene addition period.

Problems solved by technology

However, this fractional distillation process leads to loss of 4-ADPA by oxidative degradation and considerable tar formation.
This causes not only a reduction in the yield of valuable 4-ADPA, but also creates a need to handle and dispose of the tar that is formed in the bottom product of the distillation column, by, for example, incinerations.
These issues do not appear to be addressed by the prior art processes.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example a

nal Coupling Reaction of Aniline with Nitrobenzene

[0107]This example illustrates the results obtained when laboratory experiments were conducted similar to Example 13 of U.S. Pat. No. 5,608,111.

[0108]The coupling reaction was carried out in a 2 liter Glass Round Bottom flask (RB flask) equipped with a stirrer (½ moon blade Teflon™ stirrer), Dean-Stark condenser, thermometer, Teflon™ baffle, dropping funnel for nitrobenzene addition. Initially 25% aqueous TMAH solution (24.8% w / w, 680.7 gm, 168.8 gm on 100% basis, 1.86 moles) was charged into the RB flask. Water was removed by distillation under reduced pressure at 55 mm Hg to obtain an aqueous TMAH solution of 35% w / w TMAH. During this stage the temperature increased to 50-53° C. Aniline was charged (1003.9 gm, 10.76 moles) into the reactor and the distillation was continued under reduced pressure at 55 mm Hg. Water and aniline were removed by azeotropic distillation until the molar ratio of water to TMAH was about 4:1. During this ...

example 1

of Nitrobenzene in a Single Lot

[0112]This example illustrates the effect of addition of nitrobenzene in single lot after attaining the desired water to base mole ratio for the start of the coupling reaction, and its impact on volume productivity.

[0113]The reaction set up was the same as was used for Example A. Initially, aqueous TMAH solution (35% w / w, 480.5 gm, 168.18 gm on a 100% basis, 1.85 moles) was charged. Aniline was charged (1004.2 gm, 10.8 moles) into the reactor and distillation under reduced pressure was continued at 55 mm Hg. Water and aniline were removed by distillation until the molar ratio of water to TMAH was about 4:1. During this process the temperature of the reaction mass increased to 75° C. After attaining required mole ratio of water to base, nitrobenzene (218.7 gm, 1.78 moles) was added in single lot by using a dropping funnel. After nitrobenzene addition, water and aniline were continuously removed from the reaction by distillation under reduced pressure at...

example b

of the Coupling Reaction Product

[0116]This example illustrates a typical example of reduction of 4-NODPA and 4-NDPA in coupling mass.[0117]In 2 liter capacity autoclave, a coupling reaction product (900 gm) containing aniline (54%), TMA salt of 4-NODPA (25%), 4-NDPA (1.8%), phenazine (0.3%), azobenzene (1.8%) was placed. To this product was added water (307 gm) and noble metal catalyst (e.g. 5% Pd / C, 4 weight % loading on 4-NODPA+4-NDPA). The reaction mixture was heated at 80° C. under a hydrogen pressure of 15 kg / cm2. At the end of reduction (no hydrogen absorption, typically 30 minutes), the unconverted 4-NODPA and 4-NDPA content was almost negligible (

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Abstract

A process for preparing 4-aminodiphenylamine (4-ADPA) comprising steps of coupling of aniline with nitrobenzene in presence of a suitable base, e.g. tetramethylammonium hydroxide (TMAH), hydrogenation of the coupling mass, phase separation, hydrogenation of azobenzene in the separated organic mass and fractional distillation for 4-ADPA recovery. An improvement in 4-ADPA recovery and a lowering of tar formation are obtained due to azobenzene reduction prior to 4-ADPA isolation. Also a gain in volume productivity of 4-ADPA is obtained by suitably altering the batch cycle time of the coupling reaction.

Description

[0001]This application is a National Stage Application of PCT / IB2012 / 051059, filed 7 Mar. 2012, which application is incorporated herein by reference. To the extent appropriate, a claim of priority is made to the above disclosed application.FIELD OF THE INVENTION[0002]The present invention relates to a process for the manufacture of 4-aminodiphenylamine (4-ADPA), wherein 4-ADPA recovery is improved by reduction of azobenzene in the reaction mass, prior to 4-ADPA isolation by fractional distillation thereby reducing the amount of distillation residue containing tars. The present invention also relates to reductive alkylation of 4-ADPA and the alkylated p-phenylenediamine products used as antioxidants and antiozonants in rubber that may be obtained from 4-ADPA by reductive alkylation with ketones. Also, the present invention can provide better volume productivity, namely, increased 4-ADPA yield per hour per liter of reactor space, thus enhancing the commercial advantage of the process...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): C07C209/68C07C209/36C07C209/02
CPCC07C209/68C07C209/02C07C209/36C07C211/56C07C211/54
Inventor NANDI, CHINMOYGANGAL, NARENDRAPUROHIT, PRAMODKETKAR, VINAYKASHELIKAR, DILIP
Owner NOCIL